Of
the 4.9 million people with clearance to access "confidential and
secret" government information, 1.1 million, or 21 percent, work for
outside contractors, according to a report from Clapper's office.

Of the
1.4 million who have the higher "top secret" access, 483,000, or 34
percent, work for contractors....

A top secret clearance costs the government
$4,005 per investigation, according to the Government Accountability
Office. Lower-level security clearances cost $260.

Once
given security clearance, workers can access offices, files and, most
important, dedicated communications and computer networks that are
walled off from the public.

Snowden
previously worked for the CIA and likely obtained his security
clearance there. But like others who leave the government to join
private contractors, he was able to keep his clearance after he left and
began working for outside firms.

Because clearances can take months or even years to acquire, government contractors often recruit workers who already have them....

Analysts
caution that any of the 1.4 million people with access to the nation's
top secrets could have leaked information about the program — whether
they worked for a contractor or the government. It was a government employee— U.S. Army Soldier Bradley Manning — who was responsible for
the last major leak of classified material, in 2010....

Critics say reliance on contractors hasn't reduced the amount the
government spends on defense, intelligence or other programs. Rather,
they say it's just shifted work to private employersand reduced
transparency. It becomes harder to track the work of those employees and
determine whether they should all have access to government secrets.

"It's
very difficult to know what contractors are doing and what they are
billing for the work — or even whether they should be performing the
work at all," said Scott Amey, an expert in contractor oversight and
government transparency at Project on Government Oversight, a
non-partisan government accountability organization based in Washington.
"It has muddied the waters.""...